Photosynthesis is the process used by plants, algae and cyanobacteria to convert light energy into chemical energy, through a process that uses sunlight, water and carbon dioxide. This calculator helps estimate the rate of photosynthesis based on key environmental factors.
Understanding the Factors:
Light Intensity: The amount of light available to the plant. Higher intensity generally leads to a higher rate, up to a saturation point.
Carbon Dioxide Concentration: CO2 is a primary reactant in photosynthesis. Increased concentration (within limits) can boost the rate.
Temperature: Photosynthesis involves enzymes, which are sensitive to temperature. There's an optimal temperature range; rates decrease significantly outside this range.
Leaf Surface Area: A larger surface area allows for more light absorption and CO2 uptake.
How the Calculator Works:
This calculator provides a simplified estimation. It uses a model where light intensity and CO2 concentration are primary drivers, with temperature acting as a limiting factor within a certain range. Leaf surface area scales the overall potential rate.
The basic idea is that the rate is proportional to the minimum of the "limiting factors." For instance, if light is abundant but CO2 is scarce, CO2 will be the limiting factor. Similarly, if temperature is too low or too high, it will limit the process.
Where each "Factor" is a value between 0 and 1, indicating how close the condition is to optimal. The "Temperature Factor" will be 0 outside a defined optimal range.
function calculatePhotosynthesisRate() {
var leafArea = parseFloat(document.getElementById("leafSurfaceArea").value);
var lightIntensity = parseFloat(document.getElementById("lightIntensity").value);
var co2Concentration = parseFloat(document.getElementById("co2Concentration").value);
var temperature = parseFloat(document.getElementById("temperature").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous result
// — Input Validation —
if (isNaN(leafArea) || leafArea <= 0) {
resultDiv.innerHTML = "Please enter a valid positive leaf surface area.";
return;
}
if (isNaN(lightIntensity) || lightIntensity < 0) {
resultDiv.innerHTML = "Please enter a valid non-negative light intensity.";
return;
}
if (isNaN(co2Concentration) || co2Concentration 0) {
lightFactor = Math.min(lightIntensity / optimalLightIntensity, 1);
if (lightIntensity > lightSaturationPoint) {
// Slightly reduce rate if far above saturation to simulate photoinhibition (optional)
lightFactor = Math.max(0, 1 – (lightIntensity – lightSaturationPoint) / (lightSaturationPoint * 0.5));
}
}
// CO2 Concentration Factor
var co2Factor = 0;
if (co2Concentration > 0) {
co2Factor = Math.min(co2Concentration / optimalCo2, 1);
if (co2Concentration > co2SaturationPoint) {
// Slightly reduce rate if far above saturation (optional)
co2Factor = Math.max(0, 1 – (co2Concentration – co2SaturationPoint) / (co2SaturationPoint * 0.5));
}
}
// Temperature Factor (Bell-shaped curve or piecewise)
var tempFactor = 0;
if (temperature >= minTemp && temperature <= maxTemp) {
// Simple parabolic approximation around optimal temperature
var tempDifference = temperature – optimalTemp;
var deviationRange = Math.max(optimalTemp – minTemp, maxTemp – optimalTemp);
tempFactor = 1 – Math.pow(tempDifference / deviationRange, 2);
tempFactor = Math.max(0, tempFactor); // Ensure it doesn't go below 0
}
// — Final Calculation —
// The rate is limited by the most limiting factor
var overallRateLimit = Math.min(lightFactor, co2Factor, tempFactor);
// Combine factors. Leaf area directly scales potential rate.
// baseRateFactor represents a maximum potential rate per unit area under ideal conditions.
var estimatedRate = leafArea * baseRateFactor * overallRateLimit;
// Units for photosynthesis rate are often expressed as
// micromoles of CO2 fixed per square meter per second (µmol CO2 / m² / s)
// or mg CO2 per dm² per hour.
// For simplicity, we'll output a relative rate and scale it.
// Let's assume baseRateFactor corresponds to a potential of ~15 µmol CO2 / m² / s
// We need to convert leafArea from cm² to m²: leafArea / 10000
var rateInCO2_per_m2_per_s = (estimatedRate / leafArea) * 15; // Approximate scaling
resultDiv.innerHTML = "Estimated Rate of Photosynthesis: " + rateInCO2_per_m2_per_s.toFixed(2) + " µmol CO2 / m² / s (approximate)";
}
#photosynthesis-calculator {
font-family: sans-serif;
border: 1px solid #ccc;
padding: 20px;
border-radius: 8px;
max-width: 600px;
margin: 20px auto;
background-color: #f9f9f9;
}
.calculator-description {
margin-bottom: 20px;
padding-bottom: 15px;
border-bottom: 1px solid #eee;
}
.calculator-description h2, .calculator-description h3 {
color: #333;
margin-top: 0;
}
.calculator-description p {
color: #555;
line-height: 1.6;
}
.calculator-inputs label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #444;
}
.calculator-inputs input[type="number"],
.calculator-inputs input[type="text"] {
width: calc(100% – 22px);
padding: 10px;
margin-bottom: 15px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
}
.calculator-inputs button {
background-color: #4CAF50;
color: white;
padding: 12px 20px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
transition: background-color 0.3s ease;
}
.calculator-inputs button:hover {
background-color: #45a049;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
background-color: #e7f7e7;
border: 1px solid #c8e6c9;
border-radius: 4px;
text-align: center;
font-size: 1.1em;
color: #2e7d32;
}
.calculator-result strong {
font-weight: bold;
}